a) A concave mirror is a mirror used by him
b) Distance of the object u = -15cm
The distance of the image v = -60cm
Therefore magnification = – image distance/object distance
= -v/u
= -(-60cm)/(-50cm) = -4 which is the linear magnification of the image
c) Distance between the object and image = distance of screen from pole of mirror – distance of object from pole to mirror
= B’P – BP = 60cm – 50cm = 45cm